Figure 1.

20 × 100 μm2 maps of two graphene ribbons grown on the C-face of 6H-SiC. The step sizes are 0.5 and 2 μm for the X- and Y-axes, respectively. The relative extinction, the normalized intensities, and Raman
shifts of the G and 2D band are shown. The right (left) ribbon corresponds to a monolayer
(bilayer) graphene. The absolute value of the Fermi level is evaluated from the ratio
between the intensities of the 2D and G bands only for the monolayer. It corresponds
to a doping level between 3 × 1012 and 9 × 1012 cm-2 with an average of 6 × 1012 cm-2.